1. Field of the Invention
The present invention relates to a method for adapting décor prints and a device for conducting said method.
2. Description of Related Art
Substrate materials, as for instance wood-based boards, provided with a décor are typically used as floor covering or for cladding walls and ceilings. In the past, the wood-based boards used a substrate materials were often coated with a décor paper for this purpose, wherein the multiplicity of different patterned décor papers was or is not limited.
As an alternative to the use of décor papers on wood-based boards in the past the direct printing of wood-based boards as substrate materials has been developed since the printing of paper and the subsequent lamination or direct coating thereof onto the wood-based board is dispensed with.
The printing techniques primarily used in this case are the gravure printing method and the digital printing method. The gravure printing method is a printing technique in which the elements to be depicted are present as depressions in a printing form, which is inked before the printing. The printing ink is primarily located in the depressions and is transferred to the object to be printed such as, for instance, as substrate material on the basis of contact pressure of a printing form and of adhesive forces. In case of digital printing on the other hand, the printing image is transferred directly from a computer into a printing machine such as, for instance, a laser printer or inkjet printer. The user of a static printing form is dispensed with.
In the context of the technical development of the printing technology of different substrate materials it is, however, more and more focused on digital printing. While digital printing methods were used at first especially in the graphic industry as for instance advertisement agencies, advertising media or in shops, it appears in the meantime that digital printing methods are also met more frequently in other sectors of industry. There are, indeed, multiple reasons, wherein, however, two main arguments can be identified. The digital printing allows the production of a printing image with in a particular high quality due to a higher resolution and allows further a broader application spectrum with high flexibility.
Digital printing is conducted today most exclusively using the color system CYMK. The CYMK color model is a subtractive color model, wherein the abbreviation CYMK stands for the three color ingredients cyan, magenta, yellow and the black portion Key as color depth. Using this color system, a color space (Gamut) can be imaged which suffices the many requirements from different areas.
Furthermore, products shall become cheaper by mass production on one hand, and on the other hand the customer expects a larger variety, which is reflected for instance in an almost endless décor variety. A tremendous problem is thereby a prediction, which a manufacturer, for instance, of decorative surfaces for consumer goods, such as laminate floors has to make regarding the questions, which decors are accepted by the customer and which not.
When redesigning a collection, a manufacturer of decorative boards has to buy a minimum quantity of printed décor paper or printed finish films. The minimum quantity of paper is typically in the range of about 1 ton, what corresponds to about 15,000 m2. This décor paper has then to be impregnated, to be pressed on substrate boards and to be further processed. In case that exactly this décor is not successful at the market, residual quantities are created on all levels of value creation, which cannot be used anymore. The economic damage arising therefrom is considerably. Furthermore, the coloring of the décor was at least determined for the one ton of paper.
A possibility to solve this problem would be the production of all decors exclusively by means of digital printing. This has, however, the serious disadvantage that these decors are considerably more expensive in respect to the printing costs. Furthermore, the higher quality level of the decors due to the higher resolution of the digital printing could devaluate other non-digital printed decors and could thus cause sales loss of conventionally printed substrate materials.
A further increasing trend exists in lot-sizes which become constantly smaller. The digital printing technology can take this trend in general into account. Due to the high flexibility of the digital print, it is not only possible to print paper or firm sheets, but also directly substrate boards as, for instance, wood-fiber boards. Hereby some levels of value creation can be skipped in this way of further refining to semi-finished or final products, as, for instance, furniture boards, laminate floors or cladding boards, what provides a further flexibilization and simplification of the production processes.
In particular in the wood-based industry until now almost exclusively decorative surfaces have been generated using the indirect gravure printing on décor papers and had thereby to fight with increasing problems of batch sizes.
Digital printing offers a solution here. It is at the moment propagated almost exclusively, as is the indirect gravure printing, on décor paper or on pre-impregnates, as for instance, pre-resined papers. Thereby, inks on water basis are mostly used, which after printing and subsequent drying still have a certain water solubility. Since in the subsequent production of the decorative surfaces at least in case of décor papers an impregnation with water-soluble resins has to be carried out, followed by pressing in a short-cycle press, the high resolution is partially deteriorated or destroyed by dissolving the colors.
The direct printing on a substrate board, preferably a wood-based board, pre-primed if necessary, by means of digital printing would be thus a desirable solution.
When realizing the solution, however, multiple obstacles have to be overcome.
The décor papers used for indirect gravure printing have a good opacity due to their relative high pigment load. In this way the intrinsic color of the substrate shall be eliminated as far as possible. In an alternative, a primer can be applied directly onto a substrate board. When a primer is applied directly onto a substrate board, preferably a wood-based board, the primer on the substrate board should not be done too thick since otherwise the protective layers, preferably synthetic resins, applied later on, cannot penetrate the primer and thus delamination or bubbles can occur after a pressing in the short-cycle press.
On the other hand, the primer can also not be done too thin. Then, the danger exists that the substrate is not completely covered, what has a negative influence on the overall color of the décor.
A further problem is that singular batches of substrate materials can be subjected to fluctuations in the composition, what can cause differences in brightness and/or the color of the substrate board. Visible differences, in particular color deviations, between the singular product-batches can occur after printing the décor.